Amino compounds as processing stabilizers for thermoplastic materials

ABSTRACT

Compounds of the general formula (I) or (II) ##STR1## where m is 2 or 3, 
     n is an integer from 1 to 6, 
     R 1  and R 2  are, independently of one another, hydrogen, C 1  - to C 18  -alkyl, C 3  - to C 8  -alkenyl or C 5  - to C 12  cycloalkyl, R 4  and R 5  are, independently of one another, hydrogen, C 1  - to C 18  -alkyl, C 3  - to C 8  -alkenyl, C 5  - to C 12  -cycloalkyl or C 7  - to C 12  -phenylalkyl, in which the phenyl ring may be substituted by up to 3 C 1  - to C 12  -alkyl or C 1  - to C 12  -alkoxy groups, 
     X is oxygen or NR 3 , 
     R 3  is an R 1  radical or a group of the formula ##STR2## B completes a 3- to 12-membered heterocycle, A when n=1 is an aliphatic radical or unsubstituted or substituted phenyl, and 
     A when n&gt;1 is a divalent organic radical, are used as processing stabilizers for thermoplastic materials.

During the processing of thermoplastic materials at elevatedtemperatures of from 250° to 350° C., for example during extrusion,chain decomposition or cross-linking reactions occur, especially in thepresence of atmospheric oxygen, which undesirably change the mechanicaland esthetic properties of the polymers and in some cases even renderthe plastic unusable.

In order to prevent these undesirable changes, processing stabilizersmust be added to the plastics.

The prior art compounds used for this purpose include sulfides,phosphites, phosphonites or phenolic antioxidants or mixtures of suchcompounds (see R. Ga/ chter and H. Mu/ ller, Taschenbuch derKunststoff-additive, Carl Hanser Verlag, 3rd edition, Munich, Vienna,1990, p. 42-103). DE-A 11 61 897 describes the stabilization of organicsubstances against damage by atmospheric oxygen using di- or tetraminescontaining specific aromatic radicals. However, the prior art compoundsare not always satisfactory as regards effectiveness, thermal stability,low tendency to discoloration and compatibility.

It is an object of the present invention to provide novel, easilyaccessible processing stabilizers which do not have these disadvantages.

We have found that surprisingly this object is achieved by means of theamino compounds as claimed in claim 1.

The variable m is 2 or preferably 3. The variable n is an integer from 1to 6, and n is preferably 1 or 2.

Alkyl groups for R¹ to R⁵ may be branched or unbranched.

C₁ -C₁₈ -alkyl groups for R¹ to R⁵ are for example methyl, ethyl,n-propyl, iso-propyl, n-butyl, iso-butyl, n-pentyl, 2-methylbutyl, 2- or3-methylpentyl, n-hexyl, n-heptyl, n-octyl, 3-methylhexyl, n-decyl,tridecyl, lauryl or stearyl. R¹ and R² are preferably methyl, and R³ ispreferably C₁ - to C₁₈ -alkyl.

C₃ -C₈ -alkenyl groups for R¹ to R⁵ are for example 2-butenyl,2-pentenyl, 2-hexenyl, 2-heptenyl or 2-octenyl and especially allyl.

C₅ -C₁₂ -cycloalkyl groups for R¹ to R⁵ are for example cyclopentyl,cyclohexyl, 4-methylcyclohexyl, cycloheptyl, cyclooctyl or cyclododecyl.Cyclohexyl is preferred.

C₇ -C₁₂ -phenylalkyl radicals for R¹ to R⁵ are for example benzyl, 2-,3- or 4-methylbenzyl, phenylethyl, phenylpropyl, phenylbutyl, 2-, 3- or4-methoxybenzyl, 2-, 3- or 4-ethylbenzyl, 2-, 3- or 4-ethoxybenzyl or4-dodecylbenzyl. Benzyl is preferred.

Hydrogen or methyl are particularly preferred for R¹ and R² and for R⁴and R⁵. In addition, a group of the formula ##STR3## is particularlypreferred for R³.

The radical X is oxygen or NR³, where R³ has the specified meaning.

3- to 12-membered saturated or unsaturated heterocyclic radicals##STR4## are for example: ##STR5## wherein α is a number between 0 and17.

Groups derived from morpholine or piperazine are preferred.

If n=1, A may for example be, in addition to hydrogen: C₃ - to C₂₄-alkenyl such as allyl, 1-pentenyl, 1-hexenyl, 1-heptenyl, 1-octenyl,1-decenyl or 1-dodecenyl. Oleyl is preferred.

If A is C₁ - to C₆₀ -alkyl which may be interrupted by up to 29 carbonatoms or NR³, A is for example: ##STR6## wherein: p is an integer from 0to 24,

q and r are integers from 0 to 30,

s is an integer from 1 to 30,

t and n are integers from 0 to 30,

v and w are integers from 0 to 30,

x is an integer from 1 to 30, and

y and z are integers from 0 to 20.

Of these groups, CH₃ -(CH₂)_(p) radicals with p equal to 11 to 17 arepreferred.

Examples of cycloalkyl groups A are: cyclopropyl, cyclopentyl,cyclohexyl, 4-methylcyclohexyl, 2,4-dimethylcyclohexyl, cycloheptyl,cyclooctyl or cyclododecyl.

Examples of C₇ - to C₂₀ -bicycloalkyl groups A are: adamantyl, norbornylor 1- or 2-perhydronaphthyl.

If n>1, A denotes polyvalent organic radicals. Examples of C₂ - to C₂₄-alkenyl groups A are: ##STR7## wherein a is an integer from 2 to 24.

C₄ - to C₆₀ -alkylene groups, which may be interrupted up to 29 times byNR³ or oxygen, are for example: ##STR8## where b=1 to 29,

c=1 to 19,

d=1 to 14,

e=1 to 19,

f=1 to 29,

g=2 to 58,

h=2 to 58, with the proviso that g+h≦60.

C₃ - to C₁₂ -alkylene radicals which may carry up to 6 hydroxyl, C₁ - toC₄ -alkoxy, amino, or C₁ - to C₃ -hydroxy-alkyl groups, are for example:##STR9## in which each of the free bonding positions may for examplecarry a hydroxyl, amino or methoxy group, but at least one of the freebonding positions is substituted by a group of the formula ##STR10##

Examples of C₅ - to C₁₂ -cycloalkylene groups A are: ##STR11##

C₇ - to C₂₄ -bicycloalkylene or polycycloalkylene radicals are forexample: ##STR12##

The compounds of the formula (I) and their preparation are known per se.They may easily be prepared for example by Michael addition ofacrylonitrile onto monohydric or polyhydric alcohols or monoamines orpolyamines, followed by reduction of the nitrile group (see O. Bayer,Angew. Chem. 61, 229 (1949) and the literature cited therein).

The compounds as claimed in claim 1 are outstandingly suitable forstabilizing polyolefins against oxygen and heat during processing. Theyare added to the material to be stabilized in a concentration of from0.001 to 5% by weight, preferably from 0.01 to 2% by weight andparticularly preferably from 0.1 to 0.5% by weight, before said materialis processed.

All known equipment and methods for incorporating stabilizers or otheradditives into polymers may be used to mix the compounds to be usedaccording to the invention with plastics.

The organic material stabilized according to the invention may ifdesired contain further additives, eg. antioxidants, light stabilizers,metal deactivators, antistatic agents, flame inhibitors, pigments and/orfillers.

Antioxidants and light stabilizers, which may be added in addition tothe compounds I and II, are for example compounds based on stericallyhindered phenols or sulfur- or phosphorus-containing costabilizers.

Examples of such phenolic antioxidants which may be mentioned are2,6-di-tert-butyl-4-methylphenol, n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,1,3,5-tris[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionylethyl]isocyanurate, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate, α-tocopherol and/or pentaerythritoltetrakis-[β-3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

Examples of sulfur-containing antioxidants which may be mentioned aredilauryl thiodipropionate, dimyrisyl thiodiopropionate, distearylthiodipropionate, pentaerythritol tetrakis(β-laurylthiopropionate) andpentaerythritol tetrakis(β-hexylthiopropionate).

Further antioxidants and light stabilizers which may be used togetherwith the compounds I and II are for example2-(2'-hydroxyphenyl)-benzotriazoles, 2-hydroxybenzophenones, aryl estersof hydroxybenzoic acid, α-cyanocinnamic acid derivatives,benzimidazole-carboxanilides, nickel compounds, oxaanilides and HALScompounds.

Examples of plastics that may be stabilized by the compounds as claimedin claim 1 are: polymers of monoolefins and diolefins, such as lowdensity or high density polyethylene, polypropylene, linear1-polybutene, polyisoprene, polybutadiene as well as copolymers ofmonoolefins or diolefins or mixtures of the aforementioned polymers.

Compounds of the general formulae I and II form synergistic mixtureswith for example α-tocopherol. The mixing ratio may be 10:1 to 1:10. Anamine:α-tocopherol ratio of 10:1 is preferred.

Examples of compounds to be used according to the invention include:

    ______________________________________    Ex-    am-    ple    No.  Structural formula        Remarks    ______________________________________          ##STR13##                technical C.sub.13 -isomer mixture    2          ##STR14##                technical C.sub.13 -isomer mixture    3          ##STR15##                technical C.sub.13 -isomer mixture    4          ##STR16##                technical C.sub.13 -isomer mixture    5          ##STR17##                technical C.sub.13 -isomer mixture    6    H.sub.2 N(CH.sub.2).sub.3 O(CH.sub.2).sub.2 O(CH.sub.2).sub.3         NH.sub.2                  technical                                   C.sub.13 -isomer                                   mixture    7    H.sub.2 N(CH.sub.2).sub.3 O(CH.sub.2).sub.4 O(CH.sub.2).sub.3         NH.sub.2                  technical                                   C.sub.13 -isomer                                   mixture    8    H.sub.2 N(CH.sub.2).sub.3 O(CH.sub.2).sub.2 O(CH.sub.2).sub.2         O(CH.sub.2).sub.3 NH.sub.2                                   technical                                   C.sub.13 -isomer                                   mixture    9    H.sub.2 N(CH.sub.2).sub.3 O(CH.sub.2).sub.4 O(CH.sub.2).sub.4         O(CH.sub.2).sub.3 NH.sub.2                                   technical                                   C.sub.13 -isomer                                   mixture    10   H.sub.2 N(CH.sub.2).sub.3 O(CH.sub.2).sub.6 O(CH.sub.2).sub.3         NH.sub.2                  technical                                   C.sub.13 -isomer                                   mixture    11   H.sub.2 N(CH.sub.2).sub.3 OCH.sub.2 CH[O(CH.sub.2).sub.3 NH.sub.2         ](CH.sub.2).sub.3         technical         O(CH.sub.2).sub.3 NH.sub.2                                   C.sub.13 -isomer                                   mixture    12   H.sub.2 N(CH.sub.2).sub.3 O[(CH.sub.2).sub.4 O].sub.n (CH.sub.2).sub.         3 NH.sub.2                n ˜ 9.5    13   H.sub.2 N(CH.sub.2).sub.3 O[(CH.sub.2).sub.4 O].sub.n (CH.sub.2).sub.         3 NH.sub.2                n ˜ 14    14   (CH.sub.3).sub.2 N(CH.sub.2).sub.3 N(CH.sub.3)(CH.sub.2).sub.3         N(CH.sub.3).sub.2    15   H.sub.2 N(CH.sub.2).sub.3 NH(CH.sub.2).sub.2 NH(CH.sub.2).sub.3         NH.sub.2    16   (CH.sub.3).sub.2 N(CH.sub.2).sub.3 NH(CH.sub.2).sub.3 NH.sub.2    17   H.sub.2 N(CH.sub.2).sub.3 NH(CH.sub.2).sub.3 NH(CH.sub.2).sub.3         NH(CH.sub.2).sub.3         NH.sub.2    18   H.sub.2 N(CH.sub.2).sub.3 NH(CH.sub.2).sub.3 NH(CH.sub.2).sub.3         NH(CH.sub.2).sub.3         NH(CH.sub.2).sub.3 NH.sub.2    19          ##STR18##    20   (CH.sub.3).sub.2 N(CH.sub.2).sub.2 N(CH.sub.3)(CH.sub.2).sub.2         N(CH.sub.3).sub.2    ______________________________________

Use example

0.1% by weight, based on the material to be stabilized, of thestabilizer or stabilizer mixture is mixed with additive-freepolypropylene and is processed and granulated several times at 260° C.in an extruder. After the first, third and fifth passes the melt flowindex (MFI) of the substrate is measured by means of a melt viscometeraccording to DIN 53735. The experimental results are summarized in Table1.

                  TABLE I    ______________________________________    Melt flow index (MFI) of polypropylene after mutiple    processing             MFI    Stabilizer 1st pass    3rd pass 5th pass    ______________________________________    none       30.0        96.0     --.sup.1)    Comparison.sup.2)               19.5        29.0     53.5    Example 20 21.5        26.5     42.0    Example 8  25.5        44.0     55.0    Mixture 1.sup.3)               22.0        26.5     38.0    ______________________________________     .sup.1) cannot be granulated     .sup.2) compared with     ##STR19##     .sup.3) Mixture 1 is a mixture of the compound of Example 8 and     α-tocopherol in the ratio 10:1.

We claim:
 1. A process for stabilizing thermoplastic materials duringprocessing, which comprises using compounds of the formula (I) or (II)##STR20## where m is 2 or 3,n is an integer from 1 to 6, R¹ and R² are,independently of one another, hydrogen, C₁ - to C₁₈ -alkyl, C₃ - to C₈-alkenyl or C₅ - to C₁₂ -cycloalkyl, R⁴ and R⁵ are, independently of oneanother, hydrogen, C₁ - to C₁₈ -alkyl, C₃ - to C₈ -alkenyl, C₅ - to C₁₂-cycloalkyl or C₇ - to C₁₂ -phenylalkyl, in which the phenyl ring isunsubstituted or substituted by up to 3 C₁ - to C₁₂ -alkyl or C₁ - toC₁₂ -alkoxy groups, X is oxygen or NR³, R³ is an R¹ radical or a groupof the formula ##STR21## B completes a 3- to 12-membered saturated orunsaturated mononuclear or polynuclear heterocycle, which from 0 to 2additional hetero atoms selected from the group consisting of nitrogen,oxygen and sulfur, wherein the further nitrogen atoms are unsubstitutedor carry as substituents hydrogen, C₁ - to C₈ -alkyl or a group of theformula ##STR22## and for the heterocycle in addition to contain up to 3carbonyl groups, C₁ - to C₈ -alkyl, phenyl, C₇ - to C₁₂ -phenylalkyl orC₅ - to C₁₂ -cycloalkyl substituents, and A when n=1 is hydrogen, C₃ -to C₂₄ -alkenyl, C₁ - to C₆₀ -alkyl, which is uninterrupted orinterrupted by up to 29 oxygen atoms or NR³ and is unsubstituted orsubstituted by up to 6 hydroxyl or amino groups, C₃ - to C₁₂-cycloalkyl, which is unsubstituted or substituted by up to 3 C₁ - toC₁₂ -alkyl radicals, C₇ - to C₂₀ -bicycloalkyl or a group of the formula##STR23## A when n>1 is C₂ - to C₂₄ -alkylene, C₄ - to C₆₀ -alkylene,which is uninterrupted or interrupted by up to 5 NR³ groups or by up to28 oxygen atoms, C₃ - to C₁₂ -alkylene, which carries up to 6 hydroxyl,C₁ - to C₄ -alkoxy, amino or C₁ -to C₃ -hydroxyalkyl groups, C₅ - to C₁₂-cycloalkylene or C₇ -to C₂₄ -bicycloalkylene or polycycloalkylene, andwhen n>1 the alkylene radicals are divalent or higher valence, asprocessing stabilizers for thermoplastic materials.
 2. A process asclaimed in claim 1, where n is 1 or
 2. 3. A process as claimed in claim1, where R¹ and R² or R⁴ and R⁵ are, independently of one another,hydrogen or C₁ - to C₄ -alkyl.
 4. A process as claimed in claim 1, whereR¹ R² or R⁴ and R⁵ are, independently of one another, hydrogen ormethyl.
 5. A process as claimed in claim 1, where R³ is hydrogen, C₁ -to C₁₈ -alkyl or a radical of the formula ##STR24##
 6. A process asclaimed in claim 1, where B together with the nitrogen atom is a 5- or6-membered, saturated or unsaturated heterocycle.
 7. A process asclaimed in claim 1, where B together with the nitrogen is a 5- or6-membered heterocycle, which contains from 0 to 1 additional N or Oatom.
 8. A process as claimed in claim 1, where A, for n=1, is hydrogenor C₁ - to C₁₈ -alkyl.
 9. A process as claimed in claim 1, where A, forn>1, is C₂ - to C₉ -alkylene, which is from divalent to hexavalent, oris C₄ - to C₁₂ -alkylene interrupted by ##STR25##
 10. A process forstabilizing polyolefins during processing, which comprises usingcompounds of the formula (I) as claimed in claim
 1. 11. A process forstabilizing polyethylene during processing, which comprises usingcompounds of the formula (I) as claimed in claim
 1. 12. A process forstabilizing polypropylene during processing, which comprises usingcompounds of the formula (I) as claimed in claim
 1. 13. A process forstabilizing thermoplastic materials during processing, which comprisesusing synergistic mixtures of compounds of the formula (I) or (II) asclaimed in claim 1, or mixtures thereof, and α-tocopherol.
 14. A processfor stabilizing polyolefins during processing, which comprises usingmixtures as claimed in claim 13.